Can Wolbachia (Rickettsiaceae) explain female-biased sex ratios in mountain pine beetles (Coleoptera: Curculionidae)?

Abstract

AbstractWolbachia Hertig (Rickettsiales: Rickettsiaceae) is a genus of endosymbionts that are widespread in insects and can have important implications on population dynamics through cytoplasmic incompatibility or sex-ratio distortion. We considered Wolbachia as a possible explanation for female-biased sex ratios often observed in mountain pine beetle populations, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae: Scolytinae), a major pest species in western Canada whose most recent outbreak and range expansion has killed many millions of mature lodgepole pine, Pinus contorta var. latifolia Engelmann (Pinaceae). We used wsp primers to screen for Wolbachia in 10 mountain pine beetle populations with varying degrees of female bias in southeast British Columbia and southwest Alberta, Canada. We found no evidence of Wolbachia in these populations and suggest that other factors may explain the sex-ratio bias.